Process for binding pigments to glass fabrics

ABSTRACT

A PROCESS IS DISCLOSED FOR BINDING PIGMENTS TO GLASS FABRIC, SAID PROCESS COMPRISING (A) APPLYING TO THE GLASS FABRIC AN AQUEOUS EMULSION OF (1) A COPOLYMER PREPARED BY EMULSION POLYMERIZATION WHICH CONSISTS ESSENTIALLY OF (A) 50 TO 90 MOL PERCENT (CH3)2SIO UNITS AND (B) 10 TO 50 MOL PERCENT OF RSIO3/2 UNITS WHEREIN R IS AN ALKYL OR ALKENYL RADICAL CONTAINING FROM 1 TO 3 CARBON ATOMS, A PHENYL RADICAL OR A 3,3,3-TRIFLUOROPROPYL RADICAL, AND (2) A WATER DISPERSIBLE PIGMENT, AND (B) DRYING THE GLASS FABRIC. CONVENTIONAL SILICONE OR ORGANIC POST-FINISHES CAN BE APPLIED OVER THE ABOVE COMPOSITIONS.

United States Patent 3,759,740 PROCESS FOR BINDING PIGMENTS T0 GLASSFABRICS James K. Campbell, Midland, Mich., assignor to Dow CorningCorporation, Midland, Mich.

No Drawing. Original application Aug. 6, 1968, Ser. No. 750,472, nowPatent No. 3,634,297. Divided and this application May 12, 1971, Ser.No. 143,687

Int. Cl. B32b 17/10, 27/12 U.S. Cl. 117126 GS 2 Claims ABSTRACT OF THEDISCLOSURE This application is a division of application Ser. No.750,472 filed Aug. 6, 1968, now U.S. Pat. 3,634,297.

Past efforts to employ silicones as pigment binders on glass fabricshave generally been unsuccessful. Either the silicone has beenineffective as a pigment binder or, if effective, the silicone hasresulted in a stifiening of the fabric which results in an undesirablehand giving the glass fabric poor fiexural strength.

It is an object of this invention to provide a silicone pigment binderfor glass fabrics which is equal to or superior to the currentlyavailable organic pigment I binders. It is another object of thisinvention to provide a pigment binder for glass fabrics which will alsoimpart to the glass fabric a soft hand. It is a further object of thisinvention to provide a pigment binder for glass fabric which givesimproved flexural strengths and abrasion resistance to the fabric whencompared with conventional organic pigment binders presently beingemployed. Other objects and advantages of this invention will beapparent from the following detailed description of the invention, theexamples, and the claims.

This invention relates to an aqueous emulsion of a copolymer consistingessentially of (a) to 90 mol percent of (CH SiO units and (b) 10 to 50mol percent of RSiO units, wherein R is selected from the groupconsisting of alkyl and alkenyl radicals containing from 1 to 3 carbonatoms, the 3,3,3-trifluoropropyl radical, and the phenyl radical, saidcopolymer having been prepared by emulsion polymerization.

This invention also relates to a process for binding a pigment to glassfabric which comprises (A) applying to the glass fabric an aqueousemulsion of a copolymer consisting essentially of (a) 50 to 90 molpercent of (CH SiO units and (b) 10 to 50 mol percent of RSiO units,wherein R is selected from the group consisting of alkyl and alkenylradicals containing from 1 to 3 carbon atoms, the 3,3,3-trifluoropropylradical, and the phenyl radical, said copolymer having been prepared byemulsion polymerization, and (2) a water dispersible pigment, and (B)drying the glass fabric.

As can be seen from the above description of the invention, theessential component of the aqueous emulsion which functions as thepigment binder is a copolymer consisting essentially of 50 to 90 molpercent of dimethylsiloxane units and 10 to 50 mol percent of RSiOunits, wherein R is selected from the group consisting alkyl and3,759,740 Patented Sept. 18, 1973 "ice alkenyl radicals containing from1 to 3 carbon atoms, the 3,3,3-trifluoropropyl radical, and the phenylradical. By way of specific example, the R radical can be a methyl,ethyl, propyl, isopropyl, vinyl, allyl, 3,3,3-trifiuoropropyl or aphenyl radical. It is preferred at this time that R be a phenyl radical.

It will also be noted that it was indicated that the siloxane copolymermust be prepared by emulsion polymerization. The emulsion polymers canbe prepared by the processes described in detail in U.S. Pats. 2,891,920and 3,294,725, the disclosures of which are incorporated herein byreference. Broadly speaking, the emulsion polymerization processinvolves adding a mixture of either dimethyldimethoxysilane ordimethylcyclosiloxanes with RSi(OCH to an agitated surfactant-catalystmixture whereby the copolymer is formed. Alternatively, the silanesand/or siloxanes can be added sequentially to the surfactant-catalystmixture to obtain the copolymer. It has been found that in order toobtain the desired properties the ratio of the dime-thylsiloxane unitsto the silsesquioxane units must be within the range specified above. Itis preferable that the copolymer contain to 85 mol percent of thedimethylsiloxane units and 15 to 25 mol percent of the silsesquioxaneunits. So far as is known at this time the optimum copolymer is composedof percent dimethylsiloxane units and 20 mol percentphenylsilsesquioxane units. While the emulsions can be either anionic orcationic in nature, the latter is preferred at this time because it ismore compatible with the overall system.

The amount of the silicone copolymer in the aqueous emulsion is notcritical so far as is known at this time. The most significant factor inthis respect is the stability of the emulsion itself and therefore,generally speaking, the silicone solids content in the emulsiongenerally should be less than 35 percent by weight.

The amount of silicone that is applied to the glass fabric willgenerally run within the range of 0.1 to 3.0 percent by weight ofsilicone solids based on the dry weight of the glass fabric beingtreated although more than 3 percent of the silicone can be applied tothe glass fabric. Usually no significant advantages are obtained byapplying more than 1 percent of the silicone to the glass fabric.

In accordance with the process of this invention, one first applies tothe glass fabric an aqueous emulsion containing the silicone copolymerand a water dispersible pigment. After the emulsion of these twocomponents is applied to the glass fabric, the fabric is dried.

The aqueous emulsion can be applied to the glass fabric by any of theusual treatment techniques such as spraying or brushing the emulsiononto the glass fabric, or by dipping the glass fabric into the emulsion.However, for best results it is believed that the emulsion should bepadded onto the fabric using equipment that is readily available and inuse in the industry and which fits well into the current productionsystems.

After the emulsion has been applied, the glass fabric can be eitherair-dried or dried by placing it in a circulating air oven at anelevated temperature for an appropriate period of time. Obviously, airdrying in an oven for a short period of time is most desirable since itcuts down processing time.

After the fabric has been dried, a commercially available post-finisheither of the silicone or organic type can be applied by repadding withan emulsion of the posttinish composition. A post-finish is notessential, however, in order to obtain the advantages of the instantinvention.

It should be noted at this point that the particular pigment used tocolor the glass fabric is not critical so long as it is a waterdispersible pigment. Numerous lists of suitable pigments are availablein the literature and hence will not be repeated again here. The list ofpigments found on pages 128-134 of Part D in Volume 43 of the 1967Technical Manual of the American Association of Textile Chemists andColorists (AATCC) is illustrative of such lists and incorporated hereinby reference. No meaningful limits can be set with respect to the amountof pigment employed either in the emulsion nor to be deposited on thefabric since this is dependent solely on the wishes of the person dyeingthe fabric and the shade of color they wish to obtain.

Now in order that those skilled in the art may better understand how thepresent invention can be practiced, the following examples are given byway of illustration and not by way of limitation.

In the examples, the fabric samples were 9" x 18" with the 9" lengthbeing in the warp direction. After treatment the fabric samples were cutinto the necessary number and size specimens needed for the various testevaluations. For creased tensile strength evaluation, three specimenseach 1% x 9". For wash durability and handle evaluations three specimenseach 3" x 9" and for crocking resistance testing, one specimen 4" x 9".In all specimens the 9" length was in the warp direction. The specimensused for the creased tensile test were raveled from 1% to 1'" stripsremoving the outer warp fibers until the strips measured exactly 1" inwidth, then folded end to end in the 9" direction and placed in a Carverlaboratory press so that the fold was between the press plates to adistance of 1 /2 to 2". 3000 p.s.i. of pressure was applied to the foldfor seconds after which the specimens were removed and pulled on a Scotttester at a speed of 2" draw per minute until the specimen broke. Theresults are reported in the examples as pounds per square inch (p.s.i.).

Two of the specimens for wash durability were edged with an adhesive(Ubabond) to prevent fraying during the wash cycles. These edgedspecimens were washed in a washing machine (Kenmore 600) using the lowwater level, a normal wash cycle which was approximately 12 minuteslong, a hot Water Wash with 50 ml. of detergent (Tide), and a warm waterrinse. Approximately two yards of 80 x 80 cotton print cloth was addedas ballast during the washing cycle. At the end of one cycle (wash,rinse, spin) the specimens and ballast were removed and dried in anelectric dryer (Kenmore) for to 30 minutes on the wash-and-wear settingof the machine. After drying, one of the specimens and the ballast werereturned to the washing machine for two more consecutive wash cycles. Atthe end of the two wash cycles, the remaining specimen was once moredried. The washed specimens were then compared to each other and ratedon the International Geometric Scale as set forth in the AATCC TestMethod 61-1962. In this test a rating of 5 indicates no change in color,with successively lower numerical ratings indicating successively moredrastic changes in color due to washing.

Both the Wet and dry crocking resistance evaluations were done accordingto the AATOC Standard Test Method 8-1961 and rated on the AAT CC chartfor measuring transference of color. The lower the numerical rating inthe crocking resistance test, the more color that was transferred due torubbing. 5 is the best rating given in this test method and 1 is thelowest.

The Flex Life is a test of abrasion resistance and was determined bycontinuously flexing the sample until failure. This test was conductedon a Stoll flex abrader. Three pounds tension was maintained duringflexing on the /s" rod around which the fabric was wrapped.

Handle was evaluated by comparing the feel of the unwashed treated glassfabric specimens and rating them by a descriptive phrase.

EXAMPLE 1 A mixture of 1389.05 grams of distilled water, 14.15 grams ofammonium hydroxide and 43.8 grams of sodium tridecyl ether sulfate(Sipex EST-60) was heated to 60 C. and then a mixture of 480 grams ofdimethyldimethoxysilane and 198 grams of phenyltrimethoxysilane wasadded thereto with agitation over a period of about 1%. hours. After theaddition was complete, agitation was continued for an additional 30minutes after which 708.5 grams of methanol and water were distilledoff. The emulsion was then neutralized with dilute acetic acid to a pHof 7. The resulting product was an emulsion of a copolymer of molpercent of (CH SiO units and 20 mol percent of C H SiO units.

EXAMPLE 2 A mixture of 945.5 grams of distilled water, 22.5 grams ofdodecylbenzenesulfonic acid (Biosoft 5-100) and 291.1 grams ofdimethylcyclosiloxanes was agitated for about 20 minutes and thenhomogenized at 4000 p.s.i. on a Manton Gaulin homogenizer. Thehomogenized mixture was then heated to 'C., with agitation, and held atthis temperature for 2 hours. Then 240.9 grams of phenyltrimethoxysilanewas added over a period of 1 hour. Heating of the emulsion was continuedat 85 C. for another hour after addition of the silane was complete, andthen the emulsion was neutralized to a pH of 7 with a 20 percentsolution of sodium hydroxide. The resulting emulsion contained acopolymer of 76 mol percent (CH SiO units and 24 mol percent C H SiOunits.

EXAMPLE 3 Beta glass fabric was treated by padding at 40 p.s.i. from anaqueous emulsion containing a water dispersible blue pigment (AridyePadding Blue 26) and a silicone copolymer composed of 76 mol permentdimethylsiloxane units and 24 mol percent phenylsilsesquioxane unitsprepared in the manner described in Example 2. The emulsion containedabout 2.2 percent by weight of the silicone copolymer and 0.5 percent byweight of the pigment, these concentrations being such that at 40 p.s.i.padding pressure, there was an add on (based on the dry weight of thefabric) of about 0.15 percent of pigment and 0.67 percent of thesilicone pigment binder. After padding, the fabric was dried in acirculating air oven at 350 F. (177 C.) for about 2 minutes. After thisinitial padding and drying operation, some of the fabric was given apostfinish either with a commercial organic or a commercial siliconefinish. These post-finishes were also applied by padding at 40 p.s.i.from 2 percent aqueous emulsions of those finishes. Approximately 0.2percent of the post-finish based on the dry weight of the fabric wasdeposited on the fabric. After the post-finish treatment, the fabricswere again oven dried at 350 F. for 1 /2 minutes. The resulting fabricswere then cut into the appropriate test specimens and evaluated by thetests described above. An untreated piece of glass fabric was includedfor purposes gflcomparison. The test results are set forth in the tablee ow.

Wash durability Cracking resistance F Crease 1 '1 Post finish 1 wash 3washes Wet Dry lif: Untreated glass 14 13. 3 N one. 4 3 3 2 13. 7Organic a 5 5 5 3 390 24. 6 Silicone 5 4 4 2 4, 040 19. 7

Quilon S a stearate-ehrome complex. b A methyl hydrogenorganopolysiloxane emulsion.

EXAMPLE 4 ganic finish employed in Example 3. Included here forcomparison was glass fabric that was treated with a 6 for the siliconepigment binders of the previous examples, essentially identical resultsare obtained.

commercial polyethylacrylate emulsion pigment binder (A) (Rhoplex13-32). The fabrics treated with the above ma- Percent terials wereevaluated as before and the test results are 3)z O 90 set forth in thetable below. The handle of the fabric s s a/z treated with the siliconepigment binder was found to be (B) soft and smooth whereas the fabrictreated with the (CH SiO 80 acrylic pigment binder was found to be dryand raspy. C H SiO Wash durability Cracking resistance Crease Flextensile Pigment binder lwash 3washes Wet Dry life (p.s.i.)

t CH SiO 2% h fgg 5 5 4 2 507 21.5 i fibtfiifififit, e.et.ie./;:::: 5 34 3 224 Rhoplex I I-32 3 3 132 6. 1

I A polyethylaerylate emulsion.

EXAMPLE 5 (CH S1O 80 CHgSiOg g c H so 5 In this example, glass fabricwas treated with a silicone 3 7 1 3/2 pigment binder as in Example 3.However, in this exam- (D) ple, three different copolymers were employedall of which 3H, s10 g 5 were prepared from dimethylcyclosiloxanesaccording to CHFCHSiOa/2 15 the procedure described in Example 2 above.The co- E polymer composed of 76 mol percent dimethylsiloxane 5 unitsand 24 mol percent of phenylsilsesquioxane units is c 6 the copolymerspecifically prepared in that example. All 6 5 1 3/2 of these specimensof glass fabric were post-finished with (F) the commercial organicfinish of Example 3. These test 35 (CH SiO 80 specimens were evaluatedas before and the results are CH SiO 1 Set forth in the table below.CF3CH2CH3SiO3 m. 10

Wash durability Crocking resistance Crease Flex tensile Pigment binderlwash tiwashes Wet Dry lite (p.s.i.)

t CH s10-.-" gg ggggiggg gt 5 4 4 1 166 33.7 1 5 $8;535333;, 5d 11 4 3 31 B11 24331 3253M, C H iOs/z-- 5 4 2 EXAMPLE 6 That which is claimed is:

Glass fabric was treated as in Example 3 using two different siliconecopolymer pigment binders, and in the case of pigment binder A, a waterdispersible green pigment (Padding Green G) was used. Pigment binder Aconsisted of 80 mol percent dimethylsiloxane units and 20 mol percentphenylsilsesquioxane units. Pigment binder B consisted of 80 mol percentdimethylsiloxane units and 20 mol percent methylsilsesquioxane units.The glass fabric in this example was post-finished with 1.5 percent(based on the weight of the dry fabric) of a silicone copolymer composedof dimethylsiloxane units and (methyl)beta-amino-ethyl-gammaaminopropylsiloxane units. The fabrics so treated were evaluated asbefore and the test results are set forth in the table below.

When the copolymers set forth below, containing the indicated molpercents of the various units, are substituted 1. A process for bindinga pigment to a glass fabric which comprises (A)f applying to the glassfabric an aqueous emulsion (1) a copolymer consisting essentially of (a)75 to 85 mol percent of (CH SiO units and (b) 15 to 25 mol percent of CH SiO units, said copolymer having been prepared by emulsionpolymerization, and (2) a water dispersible pigment, and (B) drying theglass fabric. 2. The process as defined in claim 1 wherein (a) is molpercent, and (b) is 20 mol percent.

References Cited UNITED STATES PATENTS 2,891,920 6/1959 Hyde et a1117-161 Z A 3,494,788 2/1970 Bey 117161 Z A 2,778,746 1/1957 Steinman eta]. 117-126 G S WILLIAM D. MARTIN, Primary Examiner W. H. SCHMIDT,Assistant Examiner U.S. Cl. X.R. 117-161 ZA

